<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>优化后的立方体</title>
    <style>
        #canvas-frame{
            border: none;
            cursor: pointer;
            width: 100%;
            height: 600px;
            background: #eee;
        }
    </style>
</head>
<body>
    <div id="canvas-frame"></div>

    <script src='https://cdn.bootcss.com/three.js/r83/three.js'></script>
    <script>
        (function(){
            var renderer;
            function initThree() {
                width = document.getElementById('canvas-frame').clientWidth;
                height = document.getElementById('canvas-frame').clientHeight;
                renderer = new THREE.WebGLRenderer({
                    antialias : true
                });
                renderer.setSize(width, height);
                document.getElementById('canvas-frame').appendChild(renderer.domElement);
                renderer.setClearColor(0xFFFFFF, 1.0);
            }

            var camera;
            function initCamera() {
                camera = new THREE.PerspectiveCamera(45, width / height, 1, 10000);
                camera.position.x = 0;
                camera.position.y = 1000;
                camera.position.z = 0;
                camera.up.x = 0;
                camera.up.y = 0;
                camera.up.z = 1;
                camera.lookAt({
                    x : 0,
                    y : 0,
                    z : 0
                });
            }

            var scene;
            function initScene() {
                scene = new THREE.Scene();
            }

            var light;
            function initLight() {
                light = new THREE.DirectionalLight(0xFF0000, 1.0, 0);
                light.position.set(100, 100, 200);
                scene.add(light);
            }

            var cube;
            function initObject() {

                var geometry = new THREE.Geometry();
                var material = new THREE.LineBasicMaterial( { vertexColors: THREE.VertexColors} );
                var color1 = new THREE.Color( 0x444444 ), color2 = new THREE.Color( 0xFF0000 );

                // 线的材质可以由2点的颜色决定
                var p1 = new THREE.Vector3( -100, 0, 100 );
                var p2 = new THREE.Vector3(  100, 0, -100 );
                geometry.vertices.push(p1);
                geometry.vertices.push(p2);
                geometry.colors.push( color1, color2 );

                var line = new THREE.Line( geometry, material, THREE.LineSegments );
                scene.add(line);
            }
            function render(){
                renderer.clear();
                renderer.render(scene, camera);
                requestAnimationFrame(render);
            }

            function threeStart() {
                initThree();
                initCamera();
                initScene();
                initLight();
                initObject();
                render();
            }


            threeStart();
        })()
    </script>
</body>
</html>